Alloy for Golf Club Heads

ABSTRACT

An alloy for golf club heads includes 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, 3.5-6.0 wt % of nickel, the rest being iron and inevitable impurities.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an alloy and, more particularly, to an alloy for application in golf club heads and having a smaller specific gravity.

2. Description of the Related Art

In golfing, golf club heads are provided with weight blocks having different weights to lower the center of gravity of the golf club heads for the purposes of providing better control on the flight and landing point of the golf balls and enlarging the sweet spot area on a surface of the golf club head. Thus, even if a deviation of the hitting point on the golf ball occurs, the golf ball would not greatly deviate from the predetermined course if the hitting point falls in the sweet spot, and the landing point of the golf ball would be in the predetermined range.

However, each golf club head has a limitation to its weight. As an example, the upper limit of the weight of a No. 5 club head is 254 g. The weight-adjusting tolerance of a golf club head could be lost if the alloy for making the golf club head is heavier, not allowing mounting of an additional weight block for changing the center of gravity of the golf club head, leading to difficulties in adjustment of the center of gravity of the golf club head according to the user needs. Taiwan Patent Publication No. 438610 discloses SUS 17-4PH stainless steel alloy having a specific gravity of 7.8 g/cm³. A golf club head made from the SUS17-4PH stainless steel alloy is restricted by the specific gravity of the SUS17-4PH stainless steel alloy and, thus, does not allow mounting of an additional weight block in the golf club head for adjusting the center of gravity of the golf club head.

Furthermore, the inclination angle (the angle between a central axis of a shaft of the golf club head and the ground, wherein a sole of the golf club head rests flat on the ground) affects the hitting direction and hitting precision. A worker can slightly adjust the inclination angle according to the figure, gripping manner, habitual gesture, and swing speed of the golfer to meet different needs of different users.

Table 1 shows heat treatment values of SUS17-4PH stainless steel alloy, wherein group A was treated with solution heat treatment and rapid cooling at 1020-1060° C., group B was treated with air cooling at 470-490° C. after the same treatment as group A, group C was treated with air cooling at 540-560° C. after the same treatment as group A, group D was treated with air cooling at 570-590° C. after the same treatment as group A, and group E was treated with air cooling at 610-630° C. after the same treatment as group A.

TABLE 1 Heat Treatment Values of SUS17-4PH Stainless Steel Alloy Tensile Yield Heat strength strength treatment kgf/mm² kgf/mm² Elongation Hardness method (ksi) (ksi) (%) (HRC) A — — — 38 B 134 120 10 40 (190.4) (170.5) C 109 120 12 35 (154.9) (170.5) D 102  80 13 31 (144.9) (113.7) E  95  74 16 28 (135.0) (105.2)

As can be seen from Table 1, SUS17-4PH stainless steel alloy has a higher yield strength such that a golf club head made of SUS17-4PH stainless steel alloy is difficult to proceed with the inclination angle adjustment. Thus, if an error occurs in the inclination angle in a customized process, it is impossible to proceed with slight adjustment to make the golf club head meet the specifications, resulting in a poor yield.

Thus, a need exists for improvement to the above alloy for golf club heads.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide an alloy for golf club heads. The alloy has a smaller specific gravity such that a golf club head made of the alloy has a larger tolerance in adjustment of the center of gravity of the golf club head, allowing adjustment of the center of gravity in customization according to the user needs.

Another objective of the present invention is to provide an alloy for golf club heads. The alloy has a lower yield strength such that the angle adjustability of a golf club head made of the alloy can be increased. Thus, the inclination angle error in a customized process can be corrected by slight adjustment to increase the yield.

The present invention fulfills the above objectives by providing an alloy for golf club heads including 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, 3.5-6.0 wt % of nickel, the rest being iron and inevitable impurities.

Preferably, the alloy includes 3.8-4.8 wt % of silicon.

Preferably, the alloy includes 8.5-9.5 wt % of manganese.

Preferably, the alloy includes 15.0-16.0 wt % of chromium.

Preferably, the alloy includes 4.5-5.5 wt % of nickel.

Preferably, the ratio of silicon to manganese is 0.2-0.9.

Preferably, the ratio of nickel to chromium is 0.2-0.4.

Preferably, the alloy has a specific gravity of 7.4-7.6 g/cm³.

Preferably, he alloy has a tensile strength of 77.4-91.5 kgf/mm².

Preferably, the alloy has a tensile strength of 35.2-49.3 kgf/mm².

The specific gravity of the alloy for golf club heads according to the present invention is reduced by adjusting the ingredients. A golf club head made of the alloy for golf club heads has a larger tolerance in adjustment of the center of gravity, allowing customized adjustment of the center of gravity according to user needs.

The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The figure shows a schematic view of a golf club head according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a golf club head of this embodiment includes a club head body 11, a neck 12, and a striking plate 13. The neck 12 is provided on a side of the club head body 11 for coupling with a shaft (not shown). The club head body 11 and the neck 12 can be integrally formed. The striking plate 13 is provided on a face of the club head body 11 for hitting a ball.

An alloy for golf club heads according to the present invention can be used to make the club head body 11 and the neck 12. The alloy for golf club heads according to the present invention can be produced by the following steps.

Firstly, ingredients including a master alloy, silicon iron, manganese iron, chromium iron, and nickel are added in sequence into a high temperature furnace to melt and mix the ingredients. Specifically, the ingredients based on silicon, manganese, chromium, and nickel melt in the high temperature furnace (such as a high frequency furnace) and forms an alloy including a composition of carbon, silicon, manganese, chromium, and nickel having a certain percentage ratio among these elements. The alloy can be used as a matrix for the neck 12 and the club head body 11. In this embodiment, in addition to iron, the master alloy includes 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, and 3.5-6.0 wt % of nickel, and preferably includes 3.8-4.8 wt % of silicon, 8.5-9.5 wt % of manganese, 15.0-16.0 wt % of chromium, and 4.5-5.5 wt % of nickel. Of course, the material sources can be changed according to needs and can melt to form an iron alloy having the same composition.

Furthermore, the ingredients, i.e., the master alloy, silicon iron, manganese iron, chromium iron, and nickel, are preferably added into the high temperature furnace according to a specific melting sequence such that the molten alloy includes silicon, manganese and other components, providing the resultant alloy with appropriate characteristics. Furthermore, by adding the ingredients according to the specific melting sequence, precipitation during melting of the ingredients is avoided, avoiding low yield rate of the products of the club head body 11 and the neck 12 made subsequently. Furthermore, in this embodiment, fine grains of the ingredients are preferably used and are slowly added in a small amount many times as possible to avoid incomplete melting of ingredients due to addition of a large quantity of ingredients. Incomplete melting causes the ingredients to bond into lumps, resulting in formation of voids or bubbles in the high temperature furnace that cause potential danger.

Preferably, after the ingredients are added in sequence into the high temperature furnace and form the molten alloy, the weight ratio of the molten alloy can be measured by sampling to assure that the composition of the ingredients is maintained as follows: 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, 3.5-6.0 wt % of nickel, 1, and preferably includes 3.8-4.8 wt % of silicon, 8.5-9.5 wt % of manganese, 15.0-16.0 wt % of chromium, and 4.5-5.5 wt % of nickel, the rest being iron and inevitable impurities. By maintaining the special composition ratio of the molten alloy, an alloy with a low specific gravity and a low yield strength can be obtained after the molten alloy is cooled and solidifies.

Next, the above alloy can undergo precision casting to produce the club head body 11 and the neck 12 having specific shapes. Specifically, after the composition ratio of the molten alloy is confirmed, degassing and deslagging can be conducted before the molten alloy is discharged out of the furnace. Thus, the alloy can directly be poured into a mold for precision casting of the club head body 11 and the neck 12 (and/or the striking plate 13). A golf club head casted in this way can undergo shell vibration, degating, trimming, grinding, and polishing to form of a wedge of an iron golf club or a wood golf club without heat treatment. The resultant wedge possesses characteristics including a low specific gravity and a low yield strength.

In view of the foregoing, by the above procedures, an alloy for golf club heads according to the present invention includes 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, 3.5-6.0 wt % of nickel, the rest being iron and inevitable impurities. Preferably, the alloy includes 3.8-4.8 wt % of silicon, 8.5-9.5 wt % of manganese, 15.0-16.0 wt % of chromium, 4.5-5.5 wt % of nickel, the rest being iron and inevitable impurities. The specific gravity of the alloy is 7.4-7.6 g/cm³. Furthermore, the alloy for golf club heads has a low yield strength which is advantageous in angle adjustment of golf club heads.

Furthermore, the alloy for golf club heads according to the present invention can be used to produce bars for forging, which, in turn, can undergo several forging and pressing procedures in a predetermined number of forging molds according to the product or procedure needs, such that the outline of the bars for forging can gradually form a blank having a predetermined shape. The golf club head 1 can be obtained after several surface processing procedures.

Table 2 shows a comparison of the composition between the alloy for golf club heads according to the present invention and SUS17-4PH stainless steel alloy. By adjustment of ingredients shown in Table 2, the specific gravity of the alloy for golf club heads according to the present invention is 7.4-7.6 g/cm³, which is smaller than the specific gravity (7.715 g/cm³) of SUS17-4PH stainless steel alloy. Thus, a golf club head made from the alloy for golf club heads has a larger tolerance in adjustment of the center of gravity, allowing customized adjustment of the center of gravity according to user needs.

TABLE 2 Comparison of Composition between the Alloy of the Invention and a Conventional Alloy Fe C Si Mn Cu Ni Cr N (wt material (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) %) SUS17-4PH 0.07↓ 1.0↓ 1.0↓ 3.0-5.0 3.0-5.0 15.5-17.5 — Bal. The 0.1↓ 3.0-5.5 8.0-10.5 0.5↓ 4.5-5.5 14.5-17.0 0.1-0.25 Bal. invention

Table 3 shows a comparison of heat treatment values between the alloy for golf club heads according to the present invention and SUS17-4PH stainless steel alloy. The heat treatment was 1.5 hour of solution heat treatment and rapid cooling at 1050° C. The result showed that the alloy for golf club heads has a lower yield strength (the critical point between the elastic deformation and permanent deformation) by ingredient adjustment. Thus, permanent deformation of the golf club head made of the alloy for golf club heads is easier such that a lesser external force is required during angle adjustment, possessing better angle adjustability.

TABLE 3 Comparison of Heat Treatment Values between Alloy of the Invention and a Conventional Alloy Tensile Yield strength strength kgf/mm² kgf/mm² Elongation Hardness material (ksi) (ksi) (%) (HRC) SUS17-4PH 98.5 84.4 12 28-35 (140) (120) The invention 80.9-88.0 38.7-45.8 30-50 10-20 (115-125) (55-65)

To prove that the golf club heads made of the alloy for golf club heads according to the present invention possess better angle adjustability, the inclination angle 0 (the angle between the central axis of the neck 12 and the ground G when the club head body 1 rests flat on the ground G, see the figure) of the golf club head was adjusted by +3°, −3°, and +3° in sequence. The angle adjusting torque was measured by a torque meter, and the outer surfaces of the golf club heads were observed to check whether creases were formed.

Table 4 shows a comparison between the alloy for golf club heads according to the present invention and SUS17-4PH stainless steel alloy in the angle adjustability. The result showed that the alloy for golf club heads according to the present invention has a lower angle adjustment torque (namely, better angle adjustability). No creases were formed on the outer surfaces of the golf club heads when observed with the naked eye.

TABLE 4 Comparison between Alloy of the Invention and Conventional Alloy in Angle Adjustability Angle adjustment torque (kgfm) (flat, −3° rear material up +3°) crease SUS17-4PH 37.5 no 31.1 The invention 14.9 no 14.4

Accordingly, the alloy for golf club heads according to the present invention indeed possesses better angle adjustability by ingredient adjustment.

In view of the foregoing, the specific gravity of the alloy for golf club heads according to the present invention is reduced by adjusting the ingredients. A golf club head made of the alloy for golf club heads has a larger tolerance in adjustment of the center of gravity, allowing customized adjustment of the center of gravity according to user needs.

Furthermore, the alloy for golf club heads according to the present invention has a lower yield strength such that the angle adjustability is increased due to easy deformation of the golf club head. Thus, the inclination angle error in a customized process can be corrected by slight adjustment to increase the yield.

Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein. 

What is claimed is:
 1. An alloy for golf club heads comprising 3.0-5.5 wt % of silicon, 8.0-10.5 wt % of manganese, 14.5-17.0 wt % of chromium, 3.5-6.0 wt % of nickel, the rest being iron and inevitable impurities.
 2. The alloy for golf club heads as claimed in claim 1, wherein the alloy includes 3.8-4.8 wt % of silicon.
 3. The alloy for golf club heads as claimed in claim 1, wherein the alloy includes 8.5-9.5 wt % of manganese.
 4. The alloy for golf club heads as claimed in claim 1, wherein the alloy includes 15.0-16.0 wt % of chromium.
 5. The alloy for golf club heads as claimed in claim 1, wherein the alloy includes 4.5-5.5 wt % of nickel.
 6. The alloy for golf club heads as claimed in claim 1, wherein a ratio of silicon to manganese is 0.2-0.9.
 7. The alloy for golf club heads as claimed in claim 1, wherein a ratio of nickel to chromium is 0.2-0.4.
 8. The alloy for golf club heads as claimed in claim 1, wherein the alloy has a specific gravity of 7.4-7.6 g/cm³.
 9. The alloy for golf club heads as claimed in claim 1, wherein the alloy has a tensile strength of 77.4-91.5 kgf/mm².
 10. The alloy for golf club heads as claimed in claim 1, wherein the alloy has a tensile strength of 35.2-49.3 kgf/mm². 